Cam system for controlling transfer bits



Sept. 4, 1962 E. HANEL 3,052,109

CAM SYSTEM FOR CONTROLLING TRANSFER BITS Filed July 5, 1960 INVENTOR Ek/ALD Hif/VEL tes' The present invention relates generally to circular knitting machines and, in particular, to a cam system for controlling the transfer bits.

In the formation of the in turned welt of a stocking, the loops of the fixed initial course are taken from the cylinder needles by the transfer bits so as to transfer the loops again into the cylinder needles after a selected number of courses and to knit the loops together with a further course. In order to effect the stitch formation, it is only necessary that each transfer bit be projected only once from the dial, so that the transfer bits engage exactly one course of loops.

Knitting operations of this type, and the apparatus for performing the same, are shown and described in US. Patent No. 2,387,769, issued to Page et al. on October 30, 1945, and reference is made to this US. patent for the general arrangement and construction of apparatus With which the present invention may be used and for the operation of certain parts whose operating means are not shown in detail herein as being already known to those skilled in the art.

The projection cam for advancing the transfer bits to engage the loops must engage the first transfer bit exactly and be withdrawn immediately after engaging the last bit, so that the first following transfer bit is not projected a second time. Since it is not possible to let the projection cam fall in between the butts of two adjacent transfer bits, this process is effected in a number of steps, a number of the last transfer bits having shorter butts than the other bits.

Consequently, the projection cam can drop into the gap formed by the short butt transfer bits without damaging the butts and the short butts are not engaged, While the first transfer bit and succeeding bits having long butts are projected for the take-up.

During this operation, the projection cam can move completely into the cam groove, so as to engage the transfer bits with short butts. The projection cam is retracted after the last transfer bit has participated in the take-up. The long butt and short butt transfer bits, the cam groove, the projection cam, and means for operating the projection cam are fully shown and described in said US. Patent No. 2,387,769, particularly FIGS. and 44 through 49 thereof. Reference is made to said US. Patent No. 2,3 87,769 for a complete disclosure of these parts which, because they are known to those skilled in the prior art, are not shown or described in detail in the following description.

Prior to the present invention it was impossible to prevent the repeated projection of a number of transfer bits for a pick up during the retraction of the projection cam. Consequently, a number of loops in the following course, which in the meantime have been knitted, were picked up again.

This will be clear when reference is made to said US. Patent No. 2,387,769 wherein each of several courses of transfer bits is divided into two sections, the first section comprising transfer bits having relatively long butts and the second section comprising transfer bits having relatively short butts. The take-up operation occurs during a single course involving a first series of transfer bits with the long butts and a second series of transfer bits with the 3,5Z,l09 Patented Sept. 4, 1962 ICC short butts. This course is immediately followed by another course involving a first series of transfer bits having long butts, and a second series of transfer bits having short butts. As the projection cam projects the last transfer bit of the first course, which is a transfer bit having a short butt, the projection cam must be immediately Withdrawn. However, this operation cannot take place fast enough for the projection cam to clear the first one or more of the long butt transfer bits constituting the first section of the following course, so that several of the long butt transfer bits of the following course are projected before the projection cam can be fully retracted or withdrawn.

As a result, the loop structure is distorted at this point and has a sinudged and unattractive appearance at the transition from the in turned welt to the leg or to the after welt.

In circular knitting machines provided with one or two yarn feeds, the transition from the take-up row to the follower or second row is so slight that it requires no special attention.

However, in circular knitting machines having a plurality of yarn feeds, for example four yarn feeds, three additional rows or courses are knitted during the take-up of the initial row and a number of loop-s from the fifth following row are picked up again by the transfer bits. This further take-up, which is caused by the withdrawal of the projection cam, appears as a wide, clearly visible defect in the finished stocking at the transition from the double Welt to the leg or to the after welt of the stocking.

In view of the foregoing it is an object of the present invention to provide means resulting in the obviation of the disadvantages of the prior art and considerably improving economy and operation of circular knitting machines of the above type.

it is another object of the present invention to provide means conducive to the elimination of conspicuous defects at the transition from the inturned welt to the leg of the stocking.

It is a further object of the invention to provide a circular knitting machine of the aforesaid type having a plurality of yarn feeds, wherein the production of high quality defect-free stockings is greatly facilitated,

These and other objects of the invention will become further apparent from the following detailed description, reference being made to the accompanying drawing showing a preferred embodiment of the invention.

In the drawing which illustrates the best mode presently contemplated for carrying out the invention:

FIG. 1 is a top plan view of a cam system for the transfer bits pursuant to the present invention; and

FIG. 2 is a partial perspective view, on an enlarged scale, of the transfer bit cam system.

Briefly described, in accordance with the present invention, an additional retracting cam is provided and is movable into the cam groove, along which the butts of the transfer bits pass, at a point between the projection cam which advances the transfer bits, and the point at which the transfer of the loops to the cylinder needles is initiated. This additional retracting cam is movable into the cam groove an amount only sufiicient to engage the long butts of the transfer bits, but insuflicient to engage the short butts of the transfer bits. As stated, during the latter part of the operation of transferring the loops from the transfer bits to the cylinder needles, the projection cam is operating on the transfer bits having the the short butts and constituting the second section of the particular course. This additional retracting cam is moved into operative relation in the cam groove, so as to engage the long butts, near the latter part of the operation of transferring the loops from the transfer bit to the cylinder needles. Consequently, While the pro jection cam is being Withdrawn from engagement With the short butts, any of the following long butt transfer bits, inadvertently engaged and advanced by the projection cam, are immediately retracted by this add tional retracting cam and before they have taken part 1n the operation of transferring loops to the cylinder needles. This allows for clean separationof the take-up course from thefollowing stitch courses and, consequently, makes it possible to work the inturned welt with several yarn feeds, thus eliminating conspicuous defects in the resultant articlei Referring now to the. drawing in detail, a stationary transfer bit cam ring 6 is illustrated as formed with a groove v4 through which the butts of the transfer bits,

rotatable with the dial 5 and radially movable relative thereto, .travel during the knitting operation. One cam system for operating the transfer bits extends through a sectorA of the ringt6 whereas a second cam system for operating the transfer bits extends through a sector B. Within the sector A, the actual operation of transferring the loops to the cylinder needles takes part only through the. sector vC.

The cam system for projecting or advancing the transfer. bits. to transfer the loops back to the cylinder needles includes a projection cam 1 which is similar in construction, operation, and operating means to the-cam 186 of FIGS. 44 through 49 ofsaid Patent No. 2,387,769. Also as described in said Patent No. 2,387,769, the transfer. bitsare divided into a leading section including long butt transfer bits h and a trailing section including shortibutt transfer bits 11. As described further in said Patent No. 2,387,769, to advance the transfer bits and transfer the loops back to needles, the projection cam 1 is moved into the cam groove for a distance suflicient to engage ithexlong'butts immediately in'advance of the first long butt reaching the'position of cam 1 and, after several of the long butts have been engaged and advancedbythe' projection cam' l, the latter is moved further into groove 4 to engage the short butts. The direction of rotation of the dial 5 is indicated by the arrow P.

During the pick-up operation, all of the transfer bits, starting with the long butt transfer bit 'h are succes sively projected by the projection cam 1, pass under the then withdrawn retraction cam 2, and take the loops from the cylinder needles in the sector C. This additional retracting cam 2 is mounted on the apparatus in a position, relative to the cam ring 6, between the projection cam 1 and' the-start-of the sector C where the actual take-up operation is initiated. The cam 2 can :be-pro- During the operation of transferring the loops, the

cam 2 is moved into the-cam groove 4- only after all of the long butt transfer bits h have passed-underneath cam 2. Ascam 2 can'be projectedinto cam groove 4 an amount only sufiicient' to engage the'long butts, the low butts pass under the cam 2 and are not influenced or im eded thereby, so that they may continue to take part in the transfer of the loops.

However, a new course of stitches or loops starts with the first long butt transfer bit h following the last low butt transfer bit n of the first course. This new course must not participate in the take-up. The long butt transfer bit sinker h and all of the following long butt transfer bits h are engaged by the cam 2 and are retracted before they arrive in the loop transfer sector C. They are thus prevented from again taking up loops;

After the completion of the loop transfer'operation, the projection cam 1 is again completely retracted from the cam groove 4, being thus disconnected or rendered inoperative. During this time or periodwhich. is required for withdrawal of the projection cam or renderings.

the latter inoperative the additional retracting cam 2 becomes effective and separates the transfer course from the succeeding or following courses of loops;

Various changes and modifications maybe'madewithout departing from the spirit and scope of thepresent invention and it is intended that such obvious changesv and modifications be embraced by the annexed claims.

Having thus described theinvention, what is claimed as new and desired to be securedby- Letters Patent, -is:

1. In a circular knitting machine including a rotating dial providedwith radially movableloop transfer bits divided into a leading group of transfer bits havingrela tively long butts and a trailing group of transfer bits having relatively short butts, means forming-a circular cam groove for travel of said butts therealong, and a projection cam selectively movablepart way intosaid--groove-toengage and project the long butt-transfer bits and then movable further into said groove to engageand 'projec the short butt transfer bits, the loop transferoperation being initiated at a pre-set angular displacement of the dialbeyond theoperating point of the projection cam'and the projection cam being withdrawn immediately after engaging and projecting thelast short butt transfer, bit,

the improvement comprising a retracting'cam positioned angularly between said projection camand the point at which the transfer operation is initiated, and movable into saidgroove while'the project-ion cam is engaged with the short butt transfer bits and withdrawn following withdrawal of said projection cam.

2. The improvement in a circular-knitting machine as claimed in claim. 1, in which-saidretractingcam is movable into saidgroove. an amount only sufiicient to engage,-

the long butt transfer bits; whereby said retracting cam will withdrawany long-butt transfer bits which are inad vertently projected by said projection: camduring the time the latter is being withdrawn;-

2,387,769 Page et a1 Oct. 30,1945 

